过去完成进行式（Past Perfect Progressive Tense）
如果我们要强调较早发生事件的连续性，我们可以用过去完成进行式。占去完成进行式和现在进行式惟一不同的地方是 verb to have 的地方一定要用had 。
1. I had been watching TV before you called me.
2. I had been working hard in a company for many years before I went to college.
3. He had been studying before he went to class.
4. He had been driving all day before he went to sleep.
I. 过去完成时/过去完成进行时 练习：
1. He _____ more than 5,000 English words when he entered the university at the age of 15.
A. has learned B. would have learned C. learned D. had learned
2. They ____ on the program for almost one week before I joined them, and now we ______ on it as no good results have come out so far.
A. had been working; are still working B. had worked; were still
C. have been working; have worked D. have worked; are still working
3. Father ______ for London on business upon my arrival, so I didn't see him.
A. has left B. left C. was leaving D. had left
4. When the old man _____ to walk back to his house, the sun ____ itself behind the mountain.
A. started; had already hidden B. had started; had already hidden
C. had started; was hiding D. was starting; hid
5. The policeman's attention was suddenly caught by a small box which _____ placed under the Minister's car.
A. has been B. was being C. had been D. would be
6. — Hurry up! Alice and Sue are waiting for you at the school gate.
— Oh! I thought they ______ without me.
A.went B. are going C. have gone D. had gone
1.We ____ (look forward to) the singer’s coming before the news arrived that he was delayed by the bad weather.
2.He _____ (wait) for two hours. He was still _____(wait).
3.Mary _____ (suffer) from ill health before he was sent to hospital.
4.I _____ (see) the film before.
5.Mary _____ (do) her homework at this time last night.